Slip-resistant roofing felt

ABSTRACT

A roofing underlayment includes a flexible sheet made of felt at least partially impregnated with a coating material. The sheet is provided with at least one ridge extending in a substantially longitudinal direction. The ridge projects upwardly from the sheet and is flexible such that the ridge is collapsible when a downward force is applied thereto. The ridge is defined by a portion of the sheet. A method for making the roof underlayment is also disclosed.

FIELD OF THE INVENTION

The present invention relates to a roofing felt, and, more particularly, to a roofing felt having a slip-resist surface.

BACKGROUND OF THE INVENTION

In the past, bituminous asphalt-based felt, commonly referred to as saturated felt, has been used as an underlayment in the construction of a roof. The felt is typically applied to a completed roof deck and then covered by outer roofing materials, such as asphalt shingles, tiles and the like. Because the felt is usually made from stock paper saturated or impregnated with asphalt, it functions to provide an additional protective layer against wind, rain, etc.

One problem associated with conventional saturated felt is that it is slippery, thereby creating a potential hazard to a roofer who must walk over the felt during a roofing operation. While various remedies have been proposed for this problem (see, e.g., U.S. Pat. Nos. 5,687,517 and 6,378,259), they are not particularly suitable for use with saturated felt and/or they may not be cost-effective. In such circumstances, there is a need for a cost-effective remedy for making saturated felt more slip-resistant.

SUMMARY OF THE INVENTION

The present invention overcomes the disadvantages and shortcomings of the prior art discussed above by providing a new and improved roofing underlayment which is made from a flexible sheet of felt at least partially impregnated with a coating material. The sheet includes at least one ridge extending in a substantially longitudinal direction. The ridge projects upwardly from the sheet and is flexible such that the ridge is collapsible when a downward force is applied thereto. The ridge is also defined by a portion of the sheet.

Another aspect of the present invention involves providing a method for forming a roofing underlayment. More particularly, the method includes the steps of providing a felt sheet and then deforming the sheet so as to form a plurality of upwardly projecting ridges thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference is made to the following detailed description of an exemplary embodiment considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a roof under construction with the use of a felt sheet made in accordance with the present invention;

FIG. 2 is an enlarged perspective view of a portion of the felt sheet shown in FIG. 1;

FIGS. 3 and 4 are schematic, in-use views of the felt sheet shown in FIGS. 1 and 2;

FIG. 5 is an enlarged view of a portion of the felt sheet illustrated in FIG. 4;

FIG. 6 is a schematic view of rollers adapted for use in making the felt sheet shown in FIGS. 1 and 2;

FIG. 7 is a modified version of the felt sheet shown in FIGS. 1 and 2;

FIG. 8 is another modified version of the felt sheet shown in FIGS. 1 and 2; and

FIG. 9 is yet another modified version of the felt sheet shown in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

FIG. 1 illustrates a roof 10 which is under construction with the use of a roof underlayment 12 constructed in accordance with the present invention. The roof underlayment 12 includes a flexible felt sheet 14 made in a conventional manner. For instance, the felt sheet 14 is made from organic and/or inorganic fibers (e.g., cellulose and/or glass fibers) saturated, impregnated, coated and/or otherwise provided with a suitable material, such as asphalt, tart, other bitumen materials and non-bitumen materials (“coating materials”). Some examples of conventional felt sheets are described in U.S. Pat. Nos. 4,513,045, 4,543,158, 5,717,012 and 5,776,841, the disclosures of which are incorporated herein by reference in their entireties.

Referring to FIG. 1, in general, and to FIGS. 2 and 3 in particular, once the felt sheet 14 is made using a conventional method, it is provided with a non-planar surface profile. More particularly, the felt sheet 14 is provided with a plurality of generally parallel ridges 16 extending in a substantially longitudinal direction along the entire length of the felt sheet 14. Each of the ridges 16 is formed by a reliefed portion of the felt sheet 14 and is therefore made from the same material as the felt sheet 14 itself (e.g., organic and/or inorganic fibers saturated with a coating material). As illustrated in FIGS. 2 and 3, the ridges 16 project upwardly from the felt sheet 14, forming a complementary groove 18 beneath each of the ridges 16. Because the felt sheet 14 is flexible, each of the ridges 16 is deformable such that it can collapse easily when compressed downwardly.

FIG. 6 illustrates a pair of rollers 20, 22 adapted for use in forming the ridges 16 in the felt sheet 14. More particularly, the roller 20 has a plurality of circular grooves 24, while the roller 22 has a plurality of circular projections 26 in registry with the grooves 24. In use, the rollers 20, 22 are urged against one another such that each of the projections 26 mates with a corresponding one of the grooves 24 as the rollers 20, 22 rotate in opposite arcuate directions.

Still referring to FIG. 6, a roll of felt 28 made using a conventional process (i.e., a substantially flat sheet felt without the ridges 16) is rotatably mounted adjacent the rollers 20, 22 such that the felt 28 can be fed into the nip formed by the rollers 20, 22. As the felt 28 is fed from the roll and passes between the rollers 20, 22, the projections 26 and the grooves 24 of the rollers 20, 22, respectively, deform portions of the felt 28, thereby forming the ridges 16 and grooves 18 therein. One or both of the rollers 20, 22 can be heated so as to facilitate the formation of the ridges 16 and grooves 18. After the felt 28 passes through the rollers 20, 22, it can be rolled into a roll for transportation to a desired location.

Because of the ridges 16, the felt sheet 14 exhibits a slip-resistant characteristic. With reference to FIGS. 3 and 4, when the felt sheet 14 is installed on a pitched roof deck 30 and stepped on by a roofer, the ridges 16 collapse. As the ridges 16 collapse, they tend to fold upon themselves, thereby forming folds 32 (see FIG. 5). Once formed, the folds 32 define gripping surfaces which provide additional traction for the roofer.

It should be noted that the present invention can have numerous modifications and variations. For instance, the ridges 16 can extend along the length of the felt sheet 14 in a non-linear manner. FIG. 7 illustrates the ridges 16 extending in a sinusoidal fashion. Moreover, the ridges 16 can be provided with different shapes and/or sizes. By way of example, instead of the substantially U-shaped profile illustrated in FIGS. 2 and 3, the ridges 16 can be provided with a substantially triangular profile (see FIG. 8) or a substantially rectangular profile (see FIG. 9). Further, the ridges 16 can be formed using any mechanism which is used for forming ridges in a flexible layer or substrate.

It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims. 

1. A roofing underlayment, comprising a flexible sheet made of felt at least partially impregnated with a coating material, said sheet including at least one ridge extending in a substantially longitudinal direction, said at least one ridge projecting upwardly from said sheet and being flexible such that said at least one ridge is collapsible when a downward force is applied thereto.
 2. The roofing underlayment of claim 1, wherein said at least one ridge is defined by a portion of said sheet.
 3. The roofing underlayment of claim 2, wherein said at least one ridge is made of said felt.
 4. The roofing underlayment of claim 3, wherein said at least one ridge includes a plurality of ridges, each of which is defined by a portion of said sheet.
 5. The roofing underlayment of claim 4, wherein each of said plurality of ridges is substantially linear.
 6. The roofing underlayment of claim 5, wherein each of said plurality of ridges has a substantially U-shaped profile.
 7. The roofing underlayment of claim 5, wherein each of said plurality of ridges has a substantially triangular profile.
 8. The roofing underlayment of claim 5, wherein each of said plurality of ridges has a substantially rectangular profile.
 9. The roofing underlayment of claim 4, wherein each of said plurality of ridges is arcuate.
 10. The roofing underlayment of claim 9, wherein each of said plurality of ridges is sinusoidal.
 11. The roofing underlayment of claim 1, wherein said at least one ridge is sized and shaped so as to fold upon itself when a downward force is applied thereto.
 12. The roofing underlayment of claim 1, wherein said felt includes at least one of organic fibers and inorganic fibers impregnated with said coating material.
 13. A method for making a roofing underlayment, comprising the steps of providing a flexible sheet felt; and deforming portions of the sheet felt so as to form a plurality of upwardly projecting ridges thereon.
 14. The method of claim 12, wherein each of the ridges is flexible such that it is collapsible when a downward force is applied thereto.
 15. The method of claim 13, wherein said deforming step is performed by passing the sheet felt between a pair of rollers urged against each other.
 16. The method of claim 14, wherein one of the rollers includes a plurality of grooves and the other of the rollers include a plurality of projections, each of which is sized and shaped so as to mate with a corresponding one of the grooves. 